GENERAL SYSTEAL\TIC BACTERIOLOGY 37 



Winogradsky (1888) reported the results of a stud}- od the morphology 

 and physiologj^ of the sulphur bacteria. A number of new genera were 

 created, and several old genera brought definitely into this group. To 

 the present time the account given by this author is the only recorded 

 observation of certain of these forms. His key for the separation of 

 these sulphur genera may be translated as follows: 



Key to Winogradsky's Genera of Sulphur Bacteria (1888) 



A. Colorless sulphur bacteria. 



I. Filaments uniform in thickness, always free, motile, forming no 



gonidia Beggiatoa 



II. Filaments of variable thickness, attached forming motile rod gonidia. 



Thiothrix 



B. Red sulphur bacteria. 



I. Cells united into families. 



a. Division of cells in three planes. 



1. Families of cells small, solitary or many surrounded by a 



gelatinous cyst, swarming. . . . Thiocystis 



2. Families of cells spread out on a substrate, spherical cells 



embedded in a common gelatin, not swarming. 



Thiocapsa 



3. Families packet shaped Thiosarcina 



h. Division of cells first in three planes, then in two. Families first 

 solid, then hollow Lamprocystis 



c. Division of cells in two directions of space. Families tabular, 



tetrads, swarming Thiopedia 



d. Division of cells in one plane. 



1. Families amoeboid motile. Cells united by plasma threads. 



Amoehohacter 



2. Families with thick gelatinous cysts. Cells in common 



gelatin, very loosely embedded, swarming. 



Thiothece 



3. Families of rods united into a net. 



Thiodictyon 



4. Families solid, non-motile, of small cells closely appressed. 



Thiopolycoccus 

 II. Cells free, alwaj-s swarming. 



a. Cells cylindric-elliptic Chromatium 



b. Cells rod and spindle shaped Rhabdochromatium 



c. Cells spiral Thiospirillum 



Hansgirg (1888, p. 229) called attention anew to the parallelism ex- 

 isting in morphology in the bacteria and the algae. He gives as an 

 illustrative table the following : 



